Apparatus for filtering noise from a periodic signal

Abstract

An apparatus for filtering noise from a periodic signal defined by successive occurrences of a first deviation and a second deviation. The apparatus comprises a first delay circuit for imposing a predetermined delay period and a first gate circuit for controlling transmission of the signal, the first gate circuit being operatively connected with the first delay circuit and cooperating with the first delay circuit to delay one of the first deviation and second deviation by the delay period to produce a once-delayed signal. The apparatus further comprises a second delay circuit for imposing the predetermined delay period and a second gate circuit for controlling transmission of the once-delayed signal, the second gate circuit being operatively connected with the first gate circuit and with the second delay circuit and cooperating with the second delay circuit to delay the other of the first deviation and the second deviation by the delay period to produce a twice-delayed signal.

What is claimed is: 
     
       1. An apparatus for filtering noise from a periodic signal, said signal effecting a first deviation from a first signal level to a second signal level at a first time, and effecting a second deviation from aid second signal level to said first signal level at a second time; successive occurrences of said first deviation and said second deviation defining a signal period; at the apparatus comprising: a first delay means or imposing a predetermined delay period;   a first gate means for controlling transmission of said signal; said first gate means being operatively connected with said first delay means and cooperating with said first delay means to delay one of said first deviation and said second deviation by said delay period to produce a ones-delayed signal;   a second delay means for imposing said predetermined delay; and   a second gate means for controlling transmission of aid once-delayed signal; said second gate means being operatively connected with said first gate means and with said second delay means and cooperating with said second delay means to delay the other of said first deviation and said second deviation by said delay period to produce a twice-delayed signal;   said first delay means being operatively connected to receive said signal and said cooperation between said first delay means and said first gate means being effected by a first delay control signal generated by said first delay means; said first gate means being responsive to said first delay control signal; said first delay control signal being a derivative of said signal.   
     
     
       2. An apparatus for filtering noise from a periodic signal as recited in claim 1 wherein said first delay means is operatively connected to receive said signal and said cooperation between said first delay means and said first gate means is effected by a first delay control signal generated by said first delay means; said first gate mans being responsive to said first delay control signal; said first delay control signal being a derivative of said signal. 
     
     
       3. An apparatus for filtering noise from a periodic signal as recited in claim 1 wherein said second delay means is operatively connected to receive said once-delayed signal and said cooperation between said second delay means and said second gate means is effected by a second delay control signal generated by said second delay means; said second gate means being responsive to said second delay control signal; said second delay control signal being a derivative of said once-delayed signal. 
     
     
       4. An apparatus for filtering noise from a periodic signal as recited in claim 3 wherein the apparatus further comprises an input means for receiving said signal; an output means for outputting said twice-delayed signal; and a plurality of buffering devices; a first buffering device of said plurality of buffering devices being operatively connected to receive said signal from said input means and to transmit said signal to said first delay means and to said first gate means; a second buffering device of said plurality of buffering devices being operatively connected to receive said once-delayed signal from said first gate means and to transmit said once-delayed signal to said second delay means and to said second gate means; a third buffering device of said plurality of buffering devices being operatively connected to receive said twice-delayed signal from said second gate means and to transmit said twice-delayed signal to said output means. 
     
     
       5. An apparatus for filtering noise from a periodic signal as recited in claim 4 wherein said second buffering device comprises a latch device. 
     
     
       6. An apparatus for filtering noise from a periodic signal as recited in claim 4 wherein said first buffering device, said second buffering device, and said third buffering device each comprises an inverter. 
     
     
       7. An apparatus for filtering noise from a periodic signal as recited in claim 3 wherein said first delay means comprises a first plurality of series-connected inverters and said second delay means comprises a second plurality of series-connected inverters. 
     
     
       8. An apparatus for filtering noise from a periodic signal as recited in claim 7 wherein said first gate means comprises a first CMOS transfer gate and said second gate means comprises a second CMOS transfer gate; said first delay control signal comprising an output from the penultimate inverter of said first plurality of series-connected inverters and an output from the final inverter of said first plurality of series-connected inverters; said second delay control signal comprising an output from the penultimate inverter of said second plurality of series-connected inverters and an output from the final inverter of said second plurality of series-connected inverters. 
     
     
       9. An apparatus for filtering noise from a periodic signal as recited in claim 8 wherein the apparatus further comprises an input means or receiving said signal; an output means for outputting said twice-delayed signal; and a plurality of buffering devices; a first buffering device of said plurality of buffering devices being operatively connected to receive said signal from said input means and to transmit said signal to said first delay means and to said first gate means; a second buffering device of said plurality of buffering devices being operatively connected o receive said once-delayed signal from said first gate means and to transmit said once-delayed signal to said second delay means and to said second gate means; a third buffering device of said plurality of buffering devices being operatively connected to receive said twice-delayed signal from aid second gage means and to transmit said twice-delayed signal to said output means. 
     
     
       10. An apparatus for filtering noise from a periodic signal as recited in claim 9 wherein said second buffering device comprises a latch device. 
     
     
       11. An apparatus for filtering noise from a periodic signal as recited in claim 9 wherein said first buffering device, said second buffering device, and said third buffering device each comprises an inverter.